December 1941 - December 1942, A Slow Start
Overview:
The Allies sunk 216 Japanese merchant vessels between December 1941 and December 1942. 152 of those, over 70%, were sunk by Allied submarines. The campaign against Japanese shipping had yet to materialize into a coherent and consistent offensive. The U.S. submarine fleet was hamstrung due to defective torpedoes, competing priorities and long transit times from Allied naval bases.
To compensate for these shortcomings, Allied naval planners focused on patrolling shipping lanes, also known as, sea lines of communication (SLOCS) which converged on major shipping hubs. Similarly, Allied subs lurked off the coast of far-flung Japanese positions to sink vessels in support of larger Allied operations. It was in this way that the U.S. submarine fleet played a vital role in the Allied campaign to island hop Japanese garrisons in the Pacific.
Similarly, the Allied surface fleet and air assets were primarily concerned with beating back the Imperial Japanese Navy (IJN) and supporting offensive operations on the periphery of the Japanese Empire. In the South Pacific, the Allies sunk Japanese merchant vessels to support offensive operations in and around the islands of Guadalcanal, New Britian and New Ireland.
Expanded Legend:
- Intermittent U.S. submarine raids sank 43 vessels off the west coast of Japan throughout 1942. Subs sank vessels near port facilities in Chiba, Mie, Shizuoka and Wakayama prefectures.
- US destroyed 17 merchant ships during interdiction of the Japanese garrisons at New Britain and surrounding islands.
- U.S. Army, Marine and Naval aircraft sunk 19 vessels sunk in support of the Guadalcanal Campaign, August-December 1942. U.S. air raids sunk 11 vessels in during the naval battle of Guadalcanal 14-15 Nov 1942.
- U.S. forces destroyed ten ships of the coast of Luzon island during the Allied defense of the Philippines; islands fall to the Japanese, May 1942
- The USS Swordfish (SS-193) sank the Atsutasan Maru on 16 December 1941 off the coast of Hainan, China. The Atsuta San Maru, an army transport was the first Japanese vessel sunk by a US submarine during World War II.
- The USS Sturgeon (SS-187) sank the Montevideo Maru, a prisoner-of-war transport vessel off the Philippine coast on 1 Jul 1942 . Among the casualties were 845 Australian POWs and 208 civilian detainees. The sinking of the Montevideo Maru was the first incident of unwitting maritime fratricide during the war. The sinking also claimed the lives of 68 Japanese crewmembers.
